From: Shadowfirebird <shadowfirebird@...>
Date: 2008-07-23T20:47:58+09:00
Subject: Re: circular 'require'

*Is* there any executable code in my two example programs, other than
the "require"s?


On Wed, Jul 23, 2008 at 12:39 PM, Calamitas <calamitates@gmail.com> wrote:
> On Wed, Jul 23, 2008 at 12:18 PM, Stefano Crocco
> <stefano.crocco@alice.it> wrote:
>> On Wednesday 23 July 2008, Shadowfirebird wrote:
>>> >ruby -w test1.rb
>>>
>>> ./test1.rb:4: unititialized constant Two (NameError)
>>
>> require 'test1.rb'
>>
>> is executed:
>>
>> * the file test1.rb is read and parsed
>> * starts the execution of test1.rb
>> * the line require 'test2.rb' is executed. This means:
>>  * the file test2.rb is read and parsed
>>  * starts the execution of test2.rb
>>  * the line require 'test1.rb' is executed. This means:
>>    * the file test1.rb is read and parsed
>>    * starts the execution of test1.rb
>>    * the line require 'test2.rb' is executed. This means:
>>      ...
>
> Actually, I'm neither seeing the error the OP got, neither the endless
> loop you seem to get. Looks like a file that is required gets added to
> $" before its contents is executed, and that a file passed on the
> command line -- like the OP did, so not using the -r switch -- is not.
> So basically the execution is as follows:
>
>  * the file test1.rb is read and parsed
>  * starts the execution of test1.rb
>  * the line require 'test2.rb' is executed. This means:
>    * the file test2.rb is read and parsed
>    * adds "test2.rb" to $"
>    * the line require 'test1.rb' is executed. This means:
>      * the file test1.rb is read and parsed
>      * adds "test1.rb" to $"
>      * the line require 'test1.rb' is executed. Does nothing as
> "test1.rb" is in $"
>      * The rest of test1.rb is executed
>    * The rest of test2.rb is executed
>  * The rest of test2.rb is executed again
>
> test1.rb is executed twice, but what probably caused the error in the
> OP's original program (the OP pared it down to a point where it
> actually did "work") is the fact that "the rest of test1.rb" is
> executed before "the rest of test2.rb". It can probably be solved by
> doing "ruby -r test1.rb" instead, but that's icky. Generally, if I
> *were* to use circular requires, I'd never put "executable code" in
> either file, just "declarations". I don't use them though. Not anymore
> after I've been bitten a few times.
>
> Peter
>
>



-- 
Me, I imagine places that I have never seen / The colored lights in
fountains, blue and green / And I imagine places that I will never go
/ Behind these clouds that hang here dark and low
But it's there when I'm holding you / There when I'm sleeping too /
There when there's nothing left of me / Hanging out behind the
burned-out factories / Out of reach but leading me / Into the
beautiful sea